Hitherto, the technology disclosed in Non-Patent Document 1 has been known as a demodulation method using a plurality of antennas. The contents disclosed in this Non-Patent Document 1 are briefly described below using an accompanying drawing.
In FIG. 1, in a transmitting apparatus 30, a transmit signal A digital signal 1 and transmit signal B digital signal 2 are input to a modulated signal generation section 3. Modulated signal generation section 3 executes BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 16QAM (Quadrature Amplitude Modulation), or suchlike modulation on transmit signal A digital signal 1 and transmit signal B digital signal 2, thereby obtaining a transmit signal A baseband signal 4 and transmit signal B baseband signal 5, and sends these signals to a radio section 6.
Radio section 6 executes predetermined radio processing such as frequency conversion and amplification on transmit signal A baseband signal 4 and transmit signal B baseband signal 5, thereby obtaining a transmit signal A modulated signal 7 and transmit signal B modulated signal 8, and supplies these signals to an antenna 9 and antenna 10 respectively. By this means, transmit signal A modulated signal 7 is emitted as a radio wave from antenna 9, and transmit signal B modulated signal 8 is emitted as a radio wave from antenna 10.
In a receiving apparatus 40, a radio section 13 executes radio processing such as frequency conversion and amplification on a received signal 12 received by an antenna 11, thereby obtaining a baseband signal 14, and sends this signal to a maximum likelihood detection section 19. Similarly, a radio section 17 executes radio processing such as frequency conversion and amplification on a received signal 16 received by an antenna 15, thereby obtaining a baseband signal 18, and sends this signal to maximum likelihood detection section 19.
By detecting baseband signals 14 and 18, maximum likelihood detection section 19 obtains a transmit signal A received digital signal 20 and transmit signal B received digital signal 21. At this time, maximum likelihood detection section 19 performs Maximum Likelihood Detection (MLD) as shown in Non-Patent Document 1.    Non-patent Document 1: IEEE WCNC 1999, pp. 1038-1042, September 1999.